Abstract
Thai traditional rice wine, known as Sato, is produced from glutinous rice using a mixed-culture starter called Lookpang. This traditional method often suffers from variability and inconsistent flavor profiles. To address these issues, the study aimed to improve the quality of Thai traditional rice wine by utilizing a defined starter culture composed of high-fatty acid ethyl esters (FAEEs)-producing Saccharomyces cerevisiae and Aspergillus oryzae. The fermentation process followed a methodology similar to that used in Japanese sake production, aiming to achieve more consistent quality and flavor profiles in the final product. Furthermore, this study involved fermenting rice wine using low-cost Thai rice to enhance its value. The parental Saccharomyces cerevisiae strain, 312WT, was isolated from Thai Sugar Industry Co., Ltd., and demonstrated fermentation performance comparable to the commercial wine yeast strain EC-1118. Subsequently, conventional mutagenesis was applied to 312WT, resulting in a mutant strain, 312/6, which overproduces fatty acid ethyl esters (FAEE). Rice wine fermented with the 312/6 strain exhibited the highest concentrations of ethyl hexanoate (28.55 ± 7.91 µg/kg, OAV = 29) and ethyl octanoate (207.22 ± 51.65 µg/kg, OAV = 41). These compounds contribute sweet and sour apple flavors to beverages, respectively. Genomic DNA analysis, compared to the parental strain 312WT, demonstrated that 312/6 harbored several mutations in the fatty acid ethyl ester (FAEE) biosynthesis pathway genes (FAS1, FAS2, ACC1, EHT1, and EEB1). These genetic changes could account for the overproduction of FAEEs.